Alternate Spectrum for Broadcasting: 1605~1705 kHz
Also known as "X-band", this spectrum is used by AM broadcast stations in the US. The stations in this band were originally stations in the 540~1600 band but were experiencing interference. While the FCC's intention was for transitioning AM stations to surrender their former frequency after a transition period, approximately 25 AM stations are still running operations on both frequencies in the 540~1600 kHz band and in this band.
This spectrum includes 10 10 kHz wide channels from 1610 kHz to 1700 kHz in 10 kHz steps. Consumer-grade receivers for this spectrum are in general distribution for analog reception, limited distribution for HD Radio reception and extremely limited distribution for DRM reception. Currently, no region 2 nations have adopted DRM for this spectrum and DRM receivers for this spectrum are limited at this time to hobbyist/professional software defined radios. There are at least two prototype consumer grade receivers that can receive DRM in this spectrum. DRM is not recognized as a AM digital broadcast standard in the USA in favor of HD Radio.
Who uses it?
Domestic incumbent users: AM broadcast stations (88) and Travelers Information Stations (759). Federal TIS services mainly on 1610 kHz serving various federal locations such as national parks and monuments (unknown number).
Foreign incumbent users: AM broadcast stations (17 in Canada and 6 in Mexico).
How do they use it?
ITU Region 2 allocation: 1605~1625 is allocated to broadcasting on a primary basis. 1625~1705 is allocated to fixed, mobile and broadcasting on a co-primary basis and to radiolocation on a secondary basis governed by international footnotes 5.89 and 5.90. 5.89, which applies to 1625~1705 recognizes the RJ88 agreement and that incumbent mobile and fixed operations in this spectrum shall take into account the addition of the broadcasting allocation. Historically, there were some fixed services in the US in this spectrum including some used for public safety and remote broadcast pickup. 5.90, which applies to 1605~1705 states that in cases where a broadcast station is concerned, the service area of the maritime mobile stations in Region 1 shall be limited to ground-wave propagation (in other words, ships in European and African waters using this spectrum have no protection from the Region 2 broadcast stations except in areas very close to the boundary with Region 1). Broadcasting in this band wa smade possible by the ITU Rio De Janeiro 1988 (RJ88) Agreement.
Federal Government allocations: 1605~1615 is allocated to mobile service on a primary basis with footnotes US221 and G127. 1615~1705 is not used by Federal with a US299 footnote. US221 restricts mobile use of 1605~1615 to distribution of public service information from travelers information stations operation on 1610 kHz. US299 allocates 1615~1705 to the maritime mobile and Alaska fixed service on a secondary basis to broadcasting. G127 sates that federal TIS on 1610 kHz has co-primary status with AM broadcast assignments. Federal TIS authorized as of 8/4/94 preclude assignment for conflicting allotments.
FCC allocations: 1605~1705 is allocated to broadcasting on a primary basis with domestic footnotes US299, NG1 and NG5. The FCC further points out that this spectrum is codified in the FCC rules related to AM broadcast stations (Part 73), Alaska Fixed Service (Part 80) and Private Land Mobile (TIS stations, Part 90). US299 also allots this spectrum to maritime mobile and Alaska fixed stations on a secondary basis. NG1 authorizes TIS on a secondary basis and NG5 authroizes secondary use of AM carriers for broadcast and non-broadcast use (such as for signalling air raid sirens using subaudible tones).
Canada/Mexico allocations: Canada follows the Region 2 allocation with no additional footnotes. Mexico has several footnotes in this spectrum to state that this band is used for broadcasting (MX20), specifies the technical provision for AM stations (MX21), acknowledges the US/Mexico agreement (MX25) and that coordination with all nations other than the US is carried out with the ITU under the RJ85 agreement (MX26).
REC analysis and opinion for use as Alternate Spectrum
When the spectrum was established for broadcasting after the Rio 1985 convention, the FCC determined that it should be used for AM stations desiring to transition to a new channel in order to relieve interfernce issues on their current channel. The FCC would eventually develop a distance separation criteria similar to commercial FM and develop a table of allotments ranked by the highest interference factor. All stations followed a specific model of 10 kW daytime and 1 kW nighttime non-directional (although limited directional operations would eventually be allowed).
In 2005, a group led by the Amherst Alliance (Nick Leggett and Don Schellhardt) filed a petition that was assigned RM-11287. This petition would have established a low power AM (LPAM) service. Another petition was filed by engineer Frederick M. Baumgartner. The basis of these petitions was to create a hyperlocal radio service in the AM spectrum as an expansion to LPFM which at that time was severely restricted because of the Radio Broadcast Protection Act. Amherst's LPAM proposal also included commercial service that was "exempt from auctions". At the time, REC supported a modified version of the Baumgartner plan which limited operations to 1620~1700 kHz and used a distance separation table between stations esepcially considering that because of international agreement, all full-service AM stations in this band must follow the ITU RJ88 model of 10 kW day and 1 kW night. REC's plan would have also protected incumbent TIS facilities.
The original Report and Order in the recent AM Revitalization proceeding does address the issues with AM stations that have an additional facility in the expanded band but have not surrendered their original allotment (see paragraph 75). That same document also includes a Notice of Inquiry (see paragraph 78) related to utilization of the expanded band by new entrants.
Using the protections proposed in the REC modified Baumgartner plan and evaluating the existing full-service and TIS stations authorized in the 1620~1700 spectrum, there is currently no availability in New York, Los Angeles, Chicago and Miami. There are potential spare channels in San Francisco and Boston. Because of the extremely high concentration of pirate activity in New York and Miami, these are metropolitan areas with very extensive immigrant populations that are be disserved by mainstream AM and FM broadacsting and these are areas without no (for New York) or very massively limited (for South Florida) spectrum for LPFM in a future window.
While LPAM could bring new opportunities into some major markets, the highest priority markets will continue to be shut out.